1. Field of the Invention
The present invention relates to a radiographic apparatus in which a multiplicity of radiation sources that output radiation are dispersedly arranged.
2. Description of the Related Art
Conventionally, a radiographic apparatus using a multi-X-ray generation apparatus was proposed. The multi-X-ray generation apparatus includes a multi-electron-output device in which a multiplicity of electron output devices are arranged, and outputs multi-X-ray beams by outputting electron beams from each of the electron output devices to a target (please refer to U.S. Patent Application Publication No. 20090316860 (Patent Literature 1), for example).
However, as in the radiographic apparatus disclosed in Patent Literature 1, when electron beams are simultaneously output from a multiplicity of electron output devices to simultaneously irradiate a subject with a plurality of X-ray beams, the irradiation ranges of the plurality of X-ray beams on an X-ray detector overlap with each other. Therefore, scattered rays that cause noises are generated, and the image qualities of radiographic images deteriorate. If the electron output devices are driven one by one to output the electron beams, the influence of the scattered rays may be prevented. However, the length of time for outputting electron beams from all of the electron output devices becomes long, and a long time period is required to perform radiography.
The specification of U.S. Patent Application Publication No. 20070133747 (Patent Literature 2) also proposes a radiographic apparatus using a multi-X-ray generation apparatus that outputs multi-X-ray beams in a manner similar to the radiographic apparatus disclosed in Patent Literature 1. Patent Literature 2 proposes preventing an influence of scattered rays by dividing the irradiation range on the X-ray detector into two parts of houndstooth patterns so that the irradiation ranges of X-ray beams that are simultaneously output are not adjacent to each other on the X-ray detector.
However, even if the irradiation range of each of the X-ray beams is controlled as in the radiographic apparatus disclosed in Patent Literature 2, scattered rays overlap with each other in diagonal directions. Therefore, it is impossible to sufficiently prevent the influence of the scattered rays.
Further, in the radiographic apparatus disclosed in Patent Literature 2, a plurality of X-ray beams are output simultaneously, and the intensity of each of the plurality of X-ray beams is not always exactly the same. Since the intensities of the X-ray beams are not uniform, an uneven radiographic image may be obtained. Further, the irradiation ranges of X-rays are not always distributed as designed. When the irradiation ranges of X-rays are shifted, the image qualities of radiographic images may deteriorate.